• Investigative Magnetic Resonance Imaging
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• v.15 no.2
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• pp.91-101
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• 2011

Perfusion magnetic resonance imaging (pMRI) is a special technique for evaluation of blood flow. Exogenous pMRI methods which are dynamic susceptibility contrast (DSC) and dynamic contrast-enhanced (DCE) use an intravenous bolus injection of paramagnetic contrast agent. In contrast, an endogenous pMRM method which is arterial spin labeling (ASL) use diffusible blood in body. In order to scan pMRI in human, technical optimizations are very important according to disease conditions. For examples, DSC is popularly used in patients with acute stroke due to its short scan time, while DSC or DCE provides the various perfusion indices for patients with tumor. ASL is useful for children, women who are expected to be pregnant, and in patients with kidney diseases which are problematic in nephrogenic systemic fibrosis (NSF). Perfusion MRI does not require any injection of radioisotopes. We expect that demand for perfusion MRI will be higher in evaluating drug efficacy and other treatment effects.

• Journal of radiological science and technology
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• v.32 no.4
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• pp.461-469
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• 2009

To predict the tumor grading, various imaging modalities have been applied clinically. This study determines clinical usefulness of perfusion MRI, using relative cerebral blood volume in grading of the gliomas. We did a retrospective review of 17 patients (mean age, 57.5 years; 11 male, 6 female) who underwent perfusion MR and conventional MRI, and then correlated pathologically after operation. Statistical analysis of regional cerebral blood volume and relative cerebral blood volume(rCBV) was performed by using softwares such as PAT by SIEMENS and Xmap ver 2.0 developed by ourselves. Six patients out of 13 were low-grade gliomas while eleven patients were the high-grade gliomas. Mean relative CBV (m_rCBV/white matter) in the low-grade gliomas was 1.62, and mean relative CBV(m_rCBV/cortex) was 0.12. In the high-grade gliomas, mean relative CBV(m_rCBV/white matter) and mean relative CBV(m_rCBV/cortex) were 33.53 and 0.96. Mean relative CBV of gliomas were elevated with a statistical difference(P<.05), compared with contralateral white matter(P=.019) or cortex(P=.025). Furthermore mean relative CBV(m_rCBV/white matter) was much higher than mean relative CBV(m_rCBV/cortex). Perfusion MRI using regional cerebral blood volume and rCBV is very useful imaging modality for grading the glioma.

• Journal of radiological science and technology
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• v.34 no.4
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• pp.323-331
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• 2011

We evaluated clinical usefulness of Arterial spin labeling perfusion MR imaging on the acute ischemic cerebral infarction patients through this study. We compared 22 patients who were done with DSC imaging and ASL imaging in admitted emergency room with acute ischemic cerebral infarction, with 36 normal comparison persons (DSC image on 21persons, ASL images on 15persons). Siemens Magnetom Verio 3.0T with 12 channel head coil was used for this study. DSC image obtained 4 maps(rCBV, rCBF, rMTT, TTP) through post-processing. For qualitative analysis we compared the area of lesion macro-diagonal with the size of diffusion weighted MR image for rMTT, TTP, rCBF, rCBV, ASL maps. For Quantitative analysis we analyzed significant correlations between less than 3 cm infarction group and normal comparison group using mean relative value of flowing image with Mann-Whitney U test. TTP(95.5%) and rCBF(95.5%) maps showed high recognition rate in qualitative analysis for >3cm infarction group. The rCBF and rCBV map tests were highly related with final stage stroke areas. Mean relative value of infarction group showed a significant correlations in quantitative analysis(p<0.05). As a conclusion, arterial spin labeling image showed high lesion recognition rate in the >3cm infarction group. Mean relative values in quantitative evaluation were used for reference data. If we do more sustainable researches, ASL image will be useful for an early diagnosis of cerebral infarction, determination of the range of ischemic pneumbra and effective treatments.

• Progress in Medical Physics
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• v.24 no.2
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• pp.108-118
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• 2013

Currently, an arterial spin labeling (ASL) magnetic resonance imaging (MRI) technique does not routinely used in clinical studies to measure perfusion in brain because optimization of imaging protocol is required to obtain optimal perfusion signals. Therefore, the objective of this study was to investigate changes of perfusion-weighed signal intensities with varying several parameters on a pulsed arterial spin labeling MRI technique obtained from a 3T MRI system. We especially evaluated alternations of ASL-MRI signal intensities on special brain areas, including in brain tissues and lobes. The signal targeting with alternating radiofrequency (STAR) pulsed ASL method was scanned on five normal subjects (mean age: 36 years, range: 29~41 years) on a 3T MRI system. Four parameters were evaluated with varying: 1) the labeling gap, 2) the labeling delay time, 3) the labeling thickness, and 4) the slice scan order. Signal intensities were obtained from the perfusion-weighted imaging on the gray and white matters and brain lobes of the frontal, parietal, temporal, and occipital areas. The results of this study were summarized: 1) Perfusion-weighted signal intensities were decreased with increasing the labeling gap in the bilateral gray matter areas and were least affected on the parietal lobe, but most affected on the occipital lobe. 2) Perfusion-weighted signal intensities were decreased with increasing the labeling delay time until 400 ms, but increased up to 1,000 ms in the bilateral gray matter areas. 3) Perfusion-weighted signal intensities were increased with increasing the labeling thickness until 120 mm in both the gray and white matter. 4) Perfusion-weighted signal intensities were higher descending scans than asending scans in both the gray and white matter. We investigated changes of perfusion-weighted signal intensities with varying several parameters in the STAR ASL method. It should require having protocol optimization processing before applying in patients. It has limitations to apply the ASL method in the white matter on a 3T MRI system.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.37-44
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• 2002

신경계의 MR영상은 하드웨어적인 발달과 초고속 영상 기법으로 기존의 MRI가 제공해 줄 수 있는 해부학적 정보 외에 기능적인 정보인 물의 확산, 뇌 혈류 정보, 뇌의 기능적 지도화와 뇌대사물의 농도를 측정할 수 있게 되었다. 반전회복영상(Inversion Recovery), 확산(diffusion), 관류(profusion), 기능적(functional)영상, 뇌의 3차원 뇌표면 rendering 및 곡면재구성영상의 임상적인 의의를 알아보고자 한다.

• Investigative Magnetic Resonance Imaging
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• v.18 no.1
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• pp.7-16
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• 2014

Purpose : To evaluate the prevalence and pattern of perfusion defect (PD) on first-pass stress perfusion MR imaging in relation with the degree of left ventricular hypertrophy (LVH) and late gadolinium-enhancement (LGE) in patients with apical hypertrophic cardiomyopathy (APH). Materials and Methods: Cardiac MR imaging with first-pass stress perfusion, cine, and LGE sequence was performed in 26 patients with APH from January 2008 to December 2012. We analyzed a total of 416 segments for LV wall thickness on end-diastolic phase of cine images, and evaluated the number of hypertrophied segment and number of consecutive hypertrophied segment (NCH). We assessed the presence or absence of PD and LGE from all patients. If there was PD, we subdivided the pattern into sporadic (sporadic-PD) or ring (ring-PD). Using univariate logistic method, we obtained the independent predictor for presence of overall PD and ring-PD. Results: PD on stress perfusion MRI was observed in 20 patients (76.9%), 12 of them (60%) showed ring-PD. Maximal LV wall thickness and number of hypertrophied segment were independent predictors for overall PD (all, p < 0.05). NCH with more than 3 segments was an additional independent factor for ring-PD. However, LGE was not statistically related with PD in patients with APH. Conclusion: About three quarters of the patients with APH showed PD, most of them represented as ring-PD. LVH degree or distribution was related with pattern of PD, however, LGE was not related with PD. Therefore, the clinical significance of PD in the patients with APH seems to be different from those with non-APH, and further comparison study between the two groups should be carried out.

• Proceedings of the KSMRM Conference
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• 1997.10a
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• pp.44-44
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• 1997

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.137-137
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• 2002

목적： 동시획득 T1/T2 강조 경사자장 펄스열을 이용하여 근골격계의 종양 관류 평가를 하고자 한다. 대상 및 방법： 근골격계 양성 및 악성 종양을 대상으로 동시획득 T1/T2 강조 경사자장 펄스열을 이용하여 시간해상도를 1.2초로 하여 1000회(약20분)를 반복하여 역동적 영상을 얻는다. 각각의 TR/TE1/TE2는 10/2/8 msec이다. 각 시기에서 서로 다른 TE를 가지고 있는 두 개의 영상을 이용하여, 수학적으로 분리하여 T1과 T2 값을 얻고, 이를 시간에 따라 배열한다. 이를 통하여, T2의 경우에는 일차효과를 이용하여 조직관류량(tissue blood volume)을 측정하고, T1에서는 2구획모델을 이용하여 투과도(permeability)를 측정한다.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.103-103
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• 2002

목적：자화율 대조법을 사용한 관류 영상에서 동시획득 $T_{1}T_{2}^{*}$ 강조 경사 자장 펄스열을 사용하여 Gd-DTPA에 의한 $T_{1}T_{2}^{*}$ 감소 효과를 동시에 획득하여 종양의 치료 효과, 판정에 중요한 기준을 제시할 수 있는 정확한 관류 정보를 얻고자 한다. 대상 및 방법： Gd-DTPA에 의한 $T_{1}T_{2}^{*}$ 감소 효과를 동시에 획득하기 위하여 기존의 이중 경사자장 펄스열을 수정, 동시획득 $T_{1}T_{2}^{*}$ 강조 경사자장 펄스열을 개발하였고, 시간 해상도를 높이기 위하여 key-hole 방법을 사용하였다. 고정 phantom으로 Sephadex를 다양한 농도의 Gd-DTPA 용액에 swelling하여 사용하였고, 관류 phantom으로는 Sephadex와 Dialyzer를 사용하였다. Sephadex는 swelling 하였을 때 $T_1$, $T_2$값이 생체 조직의 값과 비슷하고, 물을 관류시킬 수 있어 생체 모형에 적합한 phantom이다 .관류 phantom은 정량 펌프에 연결하여 사용하였다. Sephadex 관류 phantom에서는 분당 약 4$m\ell$ 속도로 관류시키면서 25 mM Gd-DTPA을 0.1$m\ell$ 일시 주입하여 관류 방향에 수직인 coronal 영상을 약 15분 동안 얻었다. 투과도를 구하기 위한 phantom으로는 hollow fiber type Dialyzer를 사용하였고, in vivo에서 1차 관류 이후에 현관 밖에서의 Gd농도가 높고 혈관 내부의 농도가 낮은 상태를 만들기 위하여 fiber 바깥쪽으로 500 mM Gd-DTPA 2 ml를 미리 넣어두고 fiber 내부로 이보다 낮은 농도의 Gd 용액을 관류시키면서 약 1시간동안 영상을 얻었다. 관류 영상에서 $T_1$/$T_{2}^{*}$ 감소 효과를 구분하여 구한 $\DeltaR_1$, $\DeltaR_2$ 곡선의 적분값으로부터 관류량을 구하고, 2 구획 모델을 적용하여 투과도를 구했다.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.127-127
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• 2002

목적： 자화율 대조법을 사용한 관류 영상에서 동시획득 $T_{1}{/}T_{2}^{*}$ 강조 경사 자장 펄스열을 사용하여 Gd-DTPA에 의한 $T_{1}{/}T_{2}^{*}$ 감소 효과를 동시에 획득하여 종양의 치료 효과, 판정에 중요한 기준을 제시할 수 있는 정확한 관류 정보를 얻고자 한다. 대상 및 방법： Gd-DTPA에 의한 $T_{1}{/}T_{2}^{*}$ 감소 효과를 동시에 획득하기 위하여 기존의 이중 경사자장 펄스열을 수정, 동시획득 $T_{1}{/}T_{2}^{*}$ 강조 경사자장 펄스열을 개발하였고, 시간 해상도를 높이기 위하여 key-hole 방법을 사용하였다. 고정 phantom으로 Sephadex를 다양한 농도의 Gd-DTPA 용액에 swelling하여 사용하였고, 관류 phantom으로는 Sephadex와 Dialyzer를 사용하였다. Sephadex는 swelling 하였을 때 $T_1$, $T_2$값이 생체 조직의 값과 비슷하고, 물을 관류시킬 수 있어 생체 모형에 적합한 phantom이다. 관류 phantom은 정량 펌프에 연결하여 사용하였다. Sephadex 관류 phantom에서는 분당 약 4$m\ell$ 속도로 관류시키면서 25 mM Gd-DTPA을 0.1$m\ell$ 일시 주입하여 관류 방향에 수직인 coronal 영상을 약 15분 동안 얻었다. 투과도를 구하기 위한 phantom으로는 hollow fiber type Dialyzer를 사용하였고, in vivo에서 1차 관류 이후에 혈관 밖에서의 Gd 농도가 높고 혈관 내부의 농도가 낮은 상태를 만들기 위하여 fiber 바깥쪽으로 500mM Gd-DTPA 2$m\ell$를 미리 넣어두고 fiber 내부로 이보다 낮은 농도의 Gd 용액을 관류시키면서 약 1시간동안 영상을 얻었다. 관류 영상에서 $T_{1}{/}T_{2}^{*}$ 감소 효과를 구분하여 구한 $\Delta{R}_{1}$, $\Delta{R}_{2}^{*}$ 곡선의 적분값으로부터 관류량을 구하고, 2 구획 모델을 적용하여 투과도를 구했다.